Vesico-ureteral reflux (VUR) is a common condition seen among children with urinary tract infection (UTI). VUR is associated with serious conditions including acute pyelonephritis and permanent renal injury, leading to scarring, renal impairment ("reflux nephropathy") and end-stage renal disease. However, the optimal treatment for VUR remains unclear. Both prophylactic antibiotics and surgical correction have been widely implemented for management of children with VUR, but neither of these has been shown in prospective randomized trials to be superior in outcomes to surveillance, and both may have significant risks. The proposed research will identify the optimal initial management approach for children diagnosed with VUR, by comparing non-intervention (surveillance), prophylactic antibiotics, and surgical correction (endoscopic injection of bulking agent) in a prospective, randomized trial. In a multi-center collaboration of five clinical treatment centers and one data center, over 2 years we will enroll 600 patients with VUR (ages 10 years or less), and follow them for 2.5-4.5 years. This study will identify differences in incidence of UTI, reflux nephropathy, and other outcomes. The Brady Urological Institute and the Division of Pediatric Nephrology at Johns Hopkins Hospital are uniquely suited to the execution of the proposed research, with an integrated multi-disciplinary research team, extensive experience in the design and execution of multi-center clinical research, and substantive clinical caseload and experience in treatment of children with VUR. Much of the current management of VUR is based on case series and anecdotes. The information gained from this research has the potential to dramatically change clinical practice, by providing definitive evidence of the optimal initial management of children with VUR. Urinary tract infections in children account for over a million doctor visits per year, and 30,000-40,000 hospitalizations per year. Many of these children have vesico-ureteral reflux (a condition where urine improperly flows backwards out of the bladder toward the kidney), and this may predispose these children to urinary infections. While vesico-ureteral relux [sic] can be corrected surgically, it is unclear whether this is beneficial;this research study will compare several management approaches to vesicoureteral reflux to determine which is best